IP 8K Signal Routing from the Beijing 2022 Winter Olympics
China Media Group (CMG) used the SMPTE 2022 conference in Hollywood to give a paper on the complex IP network used for 8K broadcasts to consumers in China. The report will be available from SMPTE soon for those wishing to see the full details. Here, we present a summary of the key elements.
Below is the high-level workflow diagram. NHK camera crews captured the 8K content for the opening and closing ceremonies and four sporting events (short track, long track, and speed skating plus the big air ski competition) – all done at the Birds Nest Stadium and Capital indoor stadium in Beijing. Over 80 hours of 8K programming was produced and distributed to CMG’s 8K channel and large-screen public venues.
The network for the 8K workflow was entirely IP based. For example, live production was handled using the SMPTE ST-2110-20 protocol with four streams. Each stream carried a 4K signal created using the Square Division (SQD) technique. The content was captured in a 16:9 aspect ratio at 50 fps using HLG optimized for 1000 nits in a 10-bit 4:2:2 YCbCr format.
Twelve audio channels were transported using two ST-2110.30 streams, while ancillary metadata was transported using a single ST-2110-40 stream.
The contribution playout signal used these same ST-2110 protocols along with JPEG-XS compression. Playout was accomplished with four streams using Sony’s XAVC class300 codec at 500 Mbps, while the primary distribution signal was a single stream encoded with the China-based AVS3 codec at 80 to 120 Mbps.
A broadcast center with master control was set up in Zhangjiakou for the skiing. In Beijing, a master control was established at the International Broadcast Center (IBC), and a second master control was in the CMG office. The diagram below shows the layout for the contribution signal management.
IBC master control was responsible for distributing all public camera signals (HD to 8K), associated voice commentary, audio tracks, and the grandmaster PTP clock for the ST-2110 routing.
The network data rates and physical layer connections are shown in the following graphic. Note that the 8K content for the Bird’s Nest stadium events used dark fiber to transport the signal over a 100 Gbps network.
All signals were sent over redundant paths. The 8K configuration is shown below. A JPEG-XS compression ratio of 8:1 was used, resulting in a bandwidth of 4.2 Gbps using ST-2011-22.
The rest of the presentation described many details of the network architecture, which interested readers can access from the SMPTE paper.
As can be seen, creating an all-IP network for such a high-stakes event was a risk but apparently well executed. 8K required a little more effort but was ultimately well integrated into the network architecture and signal workflow.
